A 61 year old male presents with severe pain in the lower th…

A 61 year old male presents with severe pain in the lower thoracic and upper lumbar spine region. He reports it is getting progressively worse and describes the pain as knife-like. The pain is mostly unchanged with trunk movement or rest, but it tends to feel worse in supine. Relevant PMH includes hypothyroidism, hypertension, hypercholesterolemia, depression, and a 40 year history of smoking 1 pack/day. Which of the following is the most likely cause of his pain: